US5487182A - Hands-free module - Google Patents

Abstract

The invention relates to a hands-free module (2) for a mobile telephone (1). The hands-free module comprises a housing (11) and a cord (13) extending therefrom. Connected to the end of the cable distal from the housing is an external phone unit (14) and an external microphone (15). Mounted on the module is a connector (12) which connects the module housing (11) mechanically to the telephone housing (3) and which also connects the external phone unit (14) and the external microphone (15) electrically to the respective circuits of the internal loudspeaker and the internal microphone of the mobile telephone. The choice between the external and internal microphones is effected by a switch.

Description

This application is a continuation, of application Ser. No. 07/715,585, filed Jun. 14, 1991, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a hands-free module for a mobile telephone of the kind which includes a housing which houses electronic circuits of which one circuit is intended for an internal loudspeaker and one circuit is intended for an internal microphone.

Mobile telephones, particularly pocket-type mobile telephones and portophones are intended to be carried by hand or in a holster. It is necessary to hold the telephone in one hand when receiving or making a telephone call, which is disadvantageous when the subscriber is occupied with other work, for instance a construction worker on a construction site who holds constructions drawings in his hands while, at the same time, communicating, via the mobile telephone, with a constructional engineer seated in his office. A similar situation is one in which a person is seated and working on a portable computer while simultaneously talking into the telephone.

DISCLOSURE OF THE INVENTION

The present invention relates to a hands-free module which leaves both hands of the subscriber free during a telephone call, wherein the mobile telephone is kept in the holster or in some other place and the subscriber has a head-set or some corresponding device which is connected to the mobile telephone either directly or through the intermediary of a separate external housing connected mechanically and electrically to the mobile telephone.

No separate telephone holder shall be required when receiving or making a telephone call.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more detail with reference to the accompanying drawings, in which

FIG. 1 is a perspective view of a pocket-type mobile telephone and of a hands-free module constructed in accordance with the present invention;

FIG. 2 is a circuit diagram for the inventive hands-free module; and

FIG. 3 is a circuit diagram of one embodiment in which the module is built into the mobile telephone.

BEST MODE OF CARRYING OUT THE INVENTION

FIG. 1 illustrates a mobile telephone 1 and a hands-free module 2 constructed in accordance with the present invention. The mobile telephone 1 comprises, in a conventional manner, a housing 3, anantenna 4, adisplay window 5 and akeyboard 6 for the dialling of telephone numbers. The housing 1 accommodates conventional electronic circuits for dialling, ringing and transmitting purposes, and also a circuit for aninternal loudspeaker 7, and a further circuit for an internal microphone 8. These two latter units are positioned, for instance, in the manner illustrated in FIG. 1. The housing has abase wall 9 fitted with anelectric contact device 10, as described hereinafter.

Themodule 2 includes ahousing 11 which is external to the mobile telephone and the contours and size of which when seen in cross-section correspond to the contours of the telephone housing 3. Mounted in one wall of thehousing 11 is anelectrical contact 12 which is configured complementary to theelectrical contact 10, so as to fit thereinto. Although not shown in FIG. 1, each electrical contact includes a plurality of mutually fitting connector pins. Theelectrical contact 12 projects from the housing and is a male-type connector, whereas theconnector 10 is a female-type connector. The arrangement is such that when the male connector orplug 12 is inserted into thefemale connector 10, themodule 2 is connected mechanically to the mobile telephone 1 while electrical components in the module are connected electrically with certain electrical circuits in the mobile telephone 1, as described in more detail herebelow. When theunits 1 and 2 are connected together, themodule 2 is seated firmly on the mobile telephone 1 and appears to be an integral part of said telephone, since the shape and size of the hands-free module correspond to the shape and size of the mobile telephone.

Extending from themodule housing 11 is an electrical cord orcable 13 which has anexternal phone unit 14 connected to the outer end thereof. The cord comprises several, insulated conductors. The phone unit may conveniently be-a button-type earphone (so-called walk-man-type). A smallexternal microphone 15 is soldered firmly to one of the conductors of said cord orcable 13, inwardly of the outer end of said cord. Themicrophone 15 and thephone unit 14 are spaced some decimeters apart.

Although not shown, theexternal housing 11 has mounted therein a circuit board on which an electronic unit is mounted, as described in more detail with reference to FIG. 2.

As shown in FIG. 2, the electronic unit, here referenced 16, includes amicrophone amplifier 17, aspeaker amplifier 18 and alimiter 19. Thecord 13 is preferably a screened conductor having two signal-conductingwires 20 and 21 respectively, and an earth conductor. Thewire 20 connects themicrophone 15 with the input of themicrophone amplifier 17. The amplifier output is connected to onefixed contact 22A of aswitch 23, via connector pins (not shown) in themale contact 12 and thefemale connector 10. Theswitch 23 has a second fixed connector 22B which is connected to the internal microphone 8 via amicrophone amplifier 24. Theswitch 23 also includes amovable contact 25 which is connected to the transceiver unit of the mobile telephone. Theswitch 23 is preferably mounted on the mobile telephone 1, in the vicinity of thekeyboard 6, and may be of the spring-back type for instance. In the FIG. 2 embodiment, theswitch 23 is implemented in the form of a mechanical switch. According to the one preferred embodiment, theswitch 23 is an electronic switch implemented by a transistor circuit which is activated by manipulating the button 40.

The mobile telephone is equipped with atransceiver unit 28 for transmitting and receiving radio signals.

Thesecond wire 21 of thecord 13 connects the output of thespeaker amplifier 18 to theexternal phone unit 14. The input of the speaker amplifier is connected to the output of thelimiter 19, the input of which is connected directly to theinternal loudspeaker 7 of the mobile telephone, via connector pins (not shown) in theconnectors 12 and 10. Theloudspeaker 7 is, in turn, connected to aspeaker amplifier 26 included in the internal speaker circuit.

Thewires 20, 21 and the earth conductor may be soldered directly to the circuit board (not shown) of the electronic unit 16, or may be connected to a schematically illustratedconnector 27 which connects the cord to the electronic unit. Thisconnector 27 is shown in broken lines in FIG. 2. As will be understood, thewire 20 is slightly shorter than thewire 21, so that theexternal microphone 15 will be located at the aforesaid distance from theexternal phone unit 14. Themicrophone 15 is preferably located at a distance of from 5 to 20 cm from the phone unit. When the phone unit is fitted in the subscriber's ear, the cord will hang down, gravitationally, such that themicrophone 15 is located in a position in which the sound quality is fully satisfactory. The whole headset-assembly can be readily fitted with one hand, which is advantageous in the case of mobile telephony.

In normal use, all telephone traffic takes place through the mobile telephone 1. When the user wishes to have both hands free when making a telephone call, he connects the hands-free module 2 to the mobile telephone 1, and places thephone unit 14 in one ear and adjusts thecord 13 so that themicrophone 15 will be suspended from said ear. The mobile telephone with the module connected thereto is put aside or put down, subsequent to dialling the number required. The internal microphone 8 can be disconnected, depending on the distance to the mobile telephone. The subscriber is now able to speak freely, while leaving both hands free.

When the user has finished his telephone conversation, the connection is broken in a conventional manner, for example by manipulating certain, predetermined buttons. The user can then carry on in the performance of his work, having both hands free, and be prepared to receive a telephone call.

As an alternative to the illustratedexternal phone unit 14 and theexternal microphone 15, a conventional headset equipped with headphones can be used. Such a headset includes a microphone which is mounted on a microphone support bar capable of being moved to a position in front of the user's mouth.

FIG. 3 illustrates an embodiment in which the electronic unit of the module is connected to thetransceiver unit 28 of the mobile telephone and which is initially incorporated in the telephone housing 3. Thecord 13 of theexternal phone unit 14 and theexternal microphone 15 are connected directly to the housing 3 by means of theconnector 27. This embodiment differs from the embodiment illustrated in FIG. 2, in that themicrophone amplifier 17 is common to both the external and theinternal microphones 15 and 8. It is necessary to connect themicrophone resistors 29 and 30 between the voltage +V and the input of themicrophone amplifier 17, and the resistors must be chosen so that the external and internal microphones will obtain the desired degree of sensitivity.

Similarly, thespeaker amplifier 26 is common to both the external and the internal speakers. Speaker selection is made possible by means of aswitch 31. Theswitch 31 has amovable contact 32 which can be moved between twofixed contacts 33, 34, of which thecontact 33 is connected to theexternal phone unit 14, via afirst speaker resistor 35, and the contact 34 is connected to theinternal speaker 7, via asecond speaker resistor 36. The speaker resistors 35, 36 are chosen so that thephone unit 14 and thespeaker 7 will have the desired sensitivity.

Similar to theswitch 23, theswitch 32 is preferably implemented by a transistor circuit which is also activated by manipulating the button 40. Alternatively, theswitch 31 can be manipulated by a separate button (not shown).

Eachswitch 23, 31 may, for instance, comprise a CMOS-transistor circuit of the 4053-type.

Claims (1)

I claim:

1. A hands-free module for use with a mobile telephone, comprising:

a first microphone means;

ear phone means;

first connection means for connecting the first microphone means and said ear phone means;

a hands-free module housing provided with an insertion portion adapted for insertion into an opening provided in a housing of said mobile telephone, said insertion portion having a cross section corresponding to that of said opening,

said hands-free module housing comprising:

microphone amplifier means for said first microphone means,

limiter means for said ear phone means, and

second connector means for connecting said amplifier means and

said limiter means to microphone output means provided in said opening and for connecting said limiter means to loudspeaker output means provided in said opening.

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